As integrated circuits (ICs) become larger and larger it becomes necessary to consider structures other than planar transistors to accommodate the ever increasing number of transistors that the circuits require. One such structure is the FinFET, a field effect transistor (FET), in which the channel of the transistor is formed along the vertical sidewalls of a thin semiconductor fin that extends upwardly from a semiconductor substrate. Because the channel is formed along a vertical fin sidewall rather than along the horizontal surface of the wafer, a wide channel (and hence high performance) can be achieved without increasing the horizontal surface area of the semiconductor substrate.
The fabrication of FinFET ICs, however, encounters some processing problems. Fin fabrication requires etching trenches into a semiconductor substrate to produce the vertical fins. The fins are usually formed in a wide array that extends across an entire IC chip. Among the problems encountered are the loading effects that arise when etching a plurality of fins. Larger open areas have a tendency to produce wide fins and deep trenches while more closely spaced fins are thin with much shallower trenches. Such variance in fin width and trench depth makes reliable processing difficult because the etch results become layout and thus product dependent. A common solution to the etch pattern loading problem is to include dummy fins to achieve a regular array in which all fins can be etched equally. If the FinFET is fabricated on a semiconductor-on-insulator (SOI) substrate, the removal of the dummy fins to achieve the necessary fin-fin electrical isolation is relatively easy. On bulk semiconductor wafers, however, such dummy fin removal and electrical isolation is not easy.
Accordingly, it is desirable to provide methods for fabricating FinFET integrated circuits on bulk semiconductor substrates. In addition, it is desirable to provide methods for fabricating FinFET integrated circuits having the necessary electrical isolation between fins. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.